Mark Ruffalo reveals Avengers 4 title on Jimmy Fallon ... or did he?

Mark Ruffalo, who plays the Hulk and Bruce Banner in the Avengers movies, is known for being a bit of a blabbermouth. So fans paid attention Friday when Ruffalo and Jimmy Fallon started hyping Ruffalo's Tonight Show appearance as if Ruffalo might just drop the biggest Marvel secret: the title of Avengers 4.

Spoiler alert: it's not clear if he really says it or just moves his lips, but the show BLEEPS over it as if he really did reveal the movie's name.

Ruffalo did drop one big clue though. He tells Fallon the title is "out there," meaning anyone who wants to sort through the millions of rumors about the title can possibly find it.

Joke titles that have circulated include Avengers 4: Black Panther Goes Bye-Bye Forever, and Avengers: I Used To Be Able To Do This All Day, But Now I'm Dead. (That last one cites a famous Captain America line, and actor Chris Evans seems to have already hinted that he's done playing Cap.)

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The latest rumor, which began circulating after the Russo brothers shared a mysterious black and white photo from the set, is that the title is Avengers: Annihilation, which would certainly fit with the rumored "bloodbath" of the plot. Any and all of those could be the "out there" rumor Ruffalo mentioned on the show.

Earlier on Friday, Ruffalo tweeted at Fallon, supposedly in a panic over his slip-up, writing, "I trust that you will cut my spoiler slip on the show tonight. That was 'off the record' homey. Please don't get me in trouble with Marvel (Barry) again."

.@JimmyFallon, I trust that you will cut my spoiler slip on the show tonight. That was “off the record” homey. Please don’t get me in trouble with Marvel (Barry) again. DM me back. M

And Fallon played right along, tweeting back, "Dude, it's too late -- already sent the final show to Burbank for air. Are you sure you're gonna be in trouble? We could maybe bleep it out. What is 'DM'?"

Dude, it’s too late - already sent the final show to Burbank for air. Are you sure you’re gonna be in trouble? We could maybe bleep it out. What is “DM”? https://t.co/GMds1hGO8X

One of the spoilers Ruffalo is famous for happened at the premiere of Thor: Ragnarok in 2017. Ruffalo accidentally left his phone in live-streaming mode while it was in his pocket, and those following the stream on Instagram heard the first 15 minutes of the film (with no video, of course).

Avengers 4 is scheduled for a May 3, 2019, release in the US and April 26 in the UK, with no Australia release date known yet.